Richie Furst (Justin Timberlake) is a whiz kid when it comes to numbers, which is why he gambles online. He can make quick and easy money by playing the odds, and he uses that fast cash to pay for his expensive Princeton tuition. One day he is playing on a site and keeps losing hands that he should have statistically won. The mathematical possibility of him losing that many winnings hands in a row is so slim that he is convinced the site is rigged. After losing all of his tuition money, he realizes he has nothing left to lose, so he hops a plane to Costa Rica, where the server to the gambling site is hosted.

Upon his arrival in Costa Rica, Richie finds and confronts the owner of the site, Ivan Block (Ben Affleck), a shady businessman who has made a fortune by taking the money of people like Richie. Ivan listens to Richie's numbers and evidence of software tampering, all of which he denies. Even though he sees Richie as something of a pest, Ivan takes a shining to him and offers him a job. Richie figures that things can't possibly get any worse for him, so he takes the job.

Ivan's main squeeze, Rebecca Shafran (Gemma Arterton), is introduced to Richie, who seems to fall in love at first sight. The two try to deny their attraction for fear of angering Ivan, who gleefully feeds chickens to his pet alligators each day. He is a ruthless man who would stop at nothing to get what he wants, especially if what he wants is revenge. He is so bad that when Richie gets beat up on his account by some thugs, he merely shrugs his shoulders and blows off the incident. Unfortunately for Richie, getting beat up is just the tip of the iceberg, and soon the former student wishes he was back at Princeton. Can he go back to his old life, or is it too late to do anything except be Ivan's minion for the rest of his life?

"Runner Runner" is a thriller with a by-the-numbers plot that pits an ingénue against a crime boss, with a pretty girl caught in the middle. Though the story itself doesn't break any new ground, a few things make "Runner Runner" stand apart from other thrillers. First is the Costa Rican setting, which isn't used as often as it should be in films. The other big difference is the world of online gambling that is at the center of the plot. If Richie had been taken for all his money at a brick-and-mortar casino, he would never have gotten past security to confront the casino owner. Since the gambling action here takes place online, he can fly into Costa Rica and surprise the owner of the gambling site, which sets up the story nicely.

All of the actors do a good job with their parts, but Affleck stands out in particular. This isn't "Argo," in which he needed to embody a character who actually exists in real life. Ivan is a rich villain archetype, which means Affleck can really have some fun with the part. The actor looks like he is truly having a good time with every sneer or smile on Ivan's face, but he stops just short of chewing scenery. Affleck has played a whole lot of good guys in the past along with a few more questionable characters here and there, such as the thief he played in "The Town." Even when he plays a morally ambiguous character, he adds layers that make that character human and possibly redeemable. This is a rare chance for him to break out and be a true villain, and he clearly relishes it.

This is director Brad Furman's third feature-length film, since he had previously only directed short films. He is a young director who still has room for growth, but he does an admirable job in "Runner Runner." He takes advantage of the beachside setting, allowing it to serve as eye candy in the background while the characters plot, scheme, and backstab. It's a nice touch, showing the seeming innocence of the ocean in contrast to the lies and deceit. It shows Furman has an eye for detail that will serve him well in what looks to be a potentially long career in the film industry.